1. Field of the Invention
The present invention relates to a pivot head wrench and, in particular, to a pivot head wrench switchable between a lock mode to restrain the head from being pivoted and an unlock mode to allow the head to be pivoted.
2. Description of the Related Art
U.S. Pat. No. 7,509,893 discloses a hand tool locking device for a hand tool includes a switch member including a shank rotatably inserted in a recess defined in a head of the hand tool, and the shank includes a convex and curved surface and a flat surface. Further, a pawl and a spring are received in a passage defined in the yoke of the head of the hand tool. The pawl includes a plurality of teeth defined on a first end thereof and is pushed to engage with the head such that the teeth thereof engaging with a plurality of engaging teeth defined on the tool head when the convex and curved surface of the shank pushes a second end of the pawl. Additionally, when the shank is rotated to make the flat surface contact the second end of the pawl, the teeth of the pawl are disengaged from the engaging teeth of the head. The drawback of the design is that the hand tool requires a retaining means to prevent the spring from disengagement from the pawl, and in addition, fatigue in the elasticity of the spring prohibits the pawl from retaining the head in a desired position precisely.
The present invention is, therefore, intended to obviate or at least alleviate the problems encountered in the prior art.